Gearing can overcome weight, drag, and HP

Just read the replies to my post about my 55. There was alot being thrown around about aerodynamic drag vs HP vs whatever and Trucker40 was taking alot of heat for talking about gearing. Why is it so hard to understand that speed is just as much a product of the gearing as it is of HP, drag, or anything else just as Trucker was saying.

Example my service truck weights nearly 32000 lbs has Series 50 Detroit putting out 275 HP backed by a MD3060P Allison auomatic with 6 speeds. 1-3 are geared, 4th is direct drive, and 5 and 6 are both OD. Now based on the HP and aerodynamis's are everything theories with only 275 HP my truck shouldn't be able to go over maybe 15 MPH as it is nothing but a big, heavy, rectangluar brick. Thing is I've actually had it running 90 on the interstate when I first got it and wanted to see what it would do. Typically, on a long stretch running 75 in 6th gear the engine is only turning around 1700 RPM, and below 60 it won't get out of 5th and again stays around 1700. With the OD the engine is allowed to turn slower as not as much HP is needed to keep the load moving as it is to get it moving initially. That's why drag cars need SO many HP, not so much so they can "go fast", but rather so they can "go fast as quickly as possible". Take that same drag car and put a really high ratio rear end in it and HP or not that car isn't going to "go fast" as quickly as it did with the lower gear ratio. In that instance you sacrifice speed for time. Basically it's all a product of speed vs time and that is what HP is. One HP is the ability to move 33,000 lbs per minute just as much as it is the ability to move 1lb in 33,000 minutes. Drag car equals 33,000 lbs in one minute, weedeater motor equals 1lb in 33,000 minutes. Both examples equal out to one HP developed.

Like Trucker said it's not the HP or the drag that gives or limits top end as much as it is the gearing. If HP and aerodymnamic drag and weight were the limiting factors, again I'd be lucky to get my truck to 15 MPH on a downhill run, with a tailwind.

Stepping outside of the box a little here since I work on equipment for a living. I work on alof of older cranes set up as draglines. Take something like an old Northwest with a inline 6 cylinder Murphy diesel. The model engines they used run in those machines run in the 1000 cu in range but only put out in the neighborhood of 175 HP at 1200 RPM. Based on the HP is the limiting factor theory 175 HP is next to nothing so it shouldn't be able to do much if any work. That said with the gearing those 175 HP go through they are capable of both pulling in and simultaniously picking up a 4 cu yard drag bucket along with the material in it while at the same time swinging the house of the machine and 80-100 feet of boom all at the same time. When moving the machine those same 175 HP have no problem walking around a machine, both up and downhill, that weights over 100,000 lbs. Given the HP is the limiting factor theory those machines shouldn't even be able to move but they do, and it's all because of the gearing.

Granted Trucker used some really extreem examples but as you can see in my examples they might not be as extreem as some people think. I mean 275 HP pushing around 32,000 lbs at 90 MPH, 175 HP moving around over 100,000 lbs, neither should be possible given all of the naysayers but each instance is not only possible but proven each and every day. Would I put a 5 HP Briggs in my service truck, no, would I put it in a crane, no,it just wouldn't be practical, but given the proper gearing can it be done????You bet it can.

Now if anyone want's to see a good example of how gearing actually works and what it can do, go to Discovery Place in Charlotte, NC. They have a setup where you turn a little handle and the machine is crushing a galvanized metal trash can... length wise, not on it's side.... As you spin the dial with one finger they have a big micrometer setup on the press headso you can see it is actually moving. I forget how many turn's of the dial it takes to move the press head .001 but it is alot. Now who'd of thought you could crush a galvanized trash can by spinning a dial with one finger? Thing is it can and does happen and it's all because of gearing....

Yep, that 'ole Trucker SURE has things figured out! A TRUE asset to these Forums (and others)!

Hmmm...... I'll agree with you to a point.... My Farmall M tops out little over 20 mph in 5th gear. If I had a 6th gear to drop into, it could easily go a little faster. I think we can all agree that aerodynamics plays a very small part in the top speed of my old M. It has enough power to go faster, but not the gearing. To this point, I'm with you.... but we separate paths when you keep maintaining that horsepower is not a limiting factor on speed.

Torque is twisting effort. As the engine shaft provides twisting effort, work is done. Power is the RATE at which work is done. Any engine or other prime mover has a limited, measurable, and pretty much constant amount of torque at a given RPM.

Propelling a car, tractor, truck, or bicycle takes a certain amount of power. That power varies, with higher speed needing more power. Why? Because power is a RATE of doing work; horsepower is a fixed ratio of work output or rate of doing work as fixed by James Watt, in an effort to equate the power of his steam engine to that of a horse.

All machines have friction. Friction in the drive train, tires on the road, etc. You can reduce this friction to some extent, but it's always there. A train, running on steel rails, has rolling friction. To eliiminate this, engineers have been playing with magnetic levitation for trains. Unless your car or truck, or my old M is converted to magnetic levitation, rolling friction must be overcome. That is work. Work takes power. Moving faster takes MORE power, as power is a measure of the RATE at which work is done.

Aerodynamics comes into play as speed increases. Not much of a problem on my Farmall M, but it is a noticeable factor at highway speed. As speed increases, aerodynamic drag increases even faster. Generally, on most shapes, if you increase the speed, the drag goes up as the square of the speed. Double the speed from 50 mph to 100 mph, and the drag will likely be close to FOUR times what it was at 50 mph. Going 150 could result in needing NINE times the power to overcome the drag at 50 mph. To keep this under control at high speed, you need to start with a reasonably aerodynamic shape.

Back to friction for a moment....all gears, bearings, etc, have friction. I don't doubt that you can crush an aluminum can with one finger using enough gear resuction. Using even more reduction, you could theoretically crush that can with the power generated by my watch spring. It might take two or three weeks, but it could do it......UNLESS the friction in the gearing could not be overcome by the power source, in this case the watch spring. If the watch spring was capable of crushing the can, it would do it extremely slowly, as it doesn't have much POWER, which again is the RATE at which WORK (crushing the can) is done.

As I recall, this whole theme got started with a discussion about how fast a car could go. The faster a car goes, the more work is being done, due in part to aerodynamics. The faster a car goes, the more POWER it takes, because power is the rate, or speed of doing work. Could my 24 hp Briggs Intek lawmower engine do the field work of my Farmall M? Perhaps, if it had enough gears to go VERY SLOWLY. Could it drive my 2010 Siverado 4wd at highway speed? Probably not much more than 30mph, even if it had 100 gears, because there isn't enough POWER to do the work at the speed I want to go.

I don't know how many horsepower it takes to shove a '55 Chevy 150 mph. I don't know how many hp it takes to run a car nearly 200 mph. But I know that there is measureable amount of power needed. Going faster takes more power (and usually lots more $$) in the process! Could an old Chevy hit 150? Maybe....with enough modifications. Could a pickup truck, or service truck, or semi, or Greyhound bus go 100 mph? In many cases, the answer is probably yes, but NOT on the POWER of a lawnmower engine, regardles of how many gears it has.

Sorry I missed the earlier chat as a retired engineer energy chats get me excited lol

Theres no free lunch in energy and its basically NOT created or destroyed, only changed in form. The HP created by an engine can be converted to rotational energy and geared up or down to change RPM or torque (and HP is a function of Torque x RPM) but in so doing some of it gets lost to heat due to gear friction. If you try to gear a lil 10 HP down to pull a big high rolling friction load and anchor it so theres no slip most all the energy gets lost by its being converted to heat so nuttin left to pull the load lol

John T (old but still curious)

Your right, there is no free lunch when it comes to power.

My thing here is that given all of the theories thrown out stating that I couldn't possibly go 150 in a 3500 lb car with a 275+ HP engine due to weight, drag, etc, it means, by extension of the same theories, there is no plausible way that my 32000 lb truck with way, way more drag could run 90 with the same or lesser HP engine. The numbers just don't add up....

In the end it all comes down to one thing, every measurement here was made/stated using the speed obtained from one gear meshing with another. Granted when you throw torque converters, etc in the mix things can get screwy but when your talking steel gears directly meshed with other steel gears, the speed of each one is always going to be in proportion to the number of teeth on each gear as there is NO slippage involved. In this case the engine was turning at 6000 RPM and it's speed was being picked up by a tach sensing rotational speed off a gear driven distributor. That speed was then being transmitted one to one, directly through the transmission to the rear axel where there was a 3.23 to 1 ratio taking it out to the tires. If the engine had not had enough power to overcome the drag, the friction, and any other forces present as has been implied, then it would have stalled or at least slowed down and would not have been showing 6000+ RPM on the tach. Now if something had gotten between any of the gears and stopped them the the engine would have either stalled or broken something to keep running at speed, none of which happened.

By the same reasoning unless the tires were slipping or the clutch was slipping a significant amount (and if it were it would have been burned up in short order at that RPM) then the only conclusion was that the car had to be traveling as the stated speed as there is no way the numbers can lie in a direct coupled application such as this. Too thinking this through further I never factored that the tire I measured the circumference on was cold and not turning. Everyone knows from watching drag racing that as a tire heats up and spins faster it's circumference increases. That would have actually had me traveling faster than stated as every RPM would have resulted in a further distance traveled, but I won't even go there...

That said it would probably freak most of these guys out to see the size of the electric motor needed to turn over the shaft in an aircraft carrier when warming and cooling the turbines for operation or shutdown. If I recall correctly the one on the America (CV66) was something like 40-50 HP. That one small motor turned both an HP and an LP turbine, every gear in the main gearbox, all of the associated parts attached to the shaft in the main thrust bearing, as well as about 400 feet of shaft that was around 28 inches in diameter, and ultimately a propeller 22 feet in diameter and weighing 69,300 lbs. In other words just because it took a 25,000+ HP steam turbine engine to turn everything on that shaft fast enough to assist the other three 25,000+ HP turbines and make the ship move in excess of 30 knots (around 45 MPH) doesn't mean it took that much to overcome frictional forces and turn that same shaft at something like 1/2 RPM shaft speed. Basically anything over the 40-50 was just extra and allowed the turbine to spin the shaft and prop alot faster. As for the way the gearing is involved you ought to see what happens when that motor doesn't get decoupled from the gear train and the shaft is spun at several RPM. Pretty much what happened is the motor basically went 'supersonic', exploded off of it's mount, and flew about 40 feet across the space, bouncing off everything in it's path as it went. They said all they heard was a high pitched sound like a turbine and then a huge explosion. Fortunately no one got hurt and I unfortunately I wasn't onboard to see it happen. I actually reported aboard shortly after the incident so I did get to see the damage to the decking, lockers, railings, etc....It's amazing what that much weight can do when it's thrown with that much force...it wasn't pretty.

I guess you're just not going to give up are you Wayne?

Dear old Dad used to tell me that you could pull a freight train with a washing machine motor if you used enough gears! I kinda suspected that there would be enough friction to stall the motor in that many gears!
JMHO, Dave

HP and Watts are power measurements. Torque and RPM are just quantities. (150ftpounds on a wrench checking a head bolt does no work)So without a time component the discussions do not make sense. A 55 Chevy moved to 150 mph would suck up 450HP with a tail wind. The Kw/hr to Hp is .746 or About 1.34 Hp per KW Jim, and Welcome Back. Jim

You kind of lost me with all of that. You cannot make an engine with inadequate torque do the same work as an engine with more, regardless of gearing. Otherwise, you could stick a 3 horse lawn-mower engine into your 1 ton pickup and pull a 10,000 lb trailer well - as long as you stuck in a 20 or 30 speed gearbox.

I'm defining "work" as pulling equal loads at equal speeds.

Getting away from paper-based calculations, my 94 Ford truck - versus my 92 Dodge is a good example. My Ford has a turbo 7.3 diesel with 4.10 axles. My Dodge has a turbo-intercooled 5.9 diesel with 3.50 axles. Seems the Ford with the bigger engine and better gearing ought to at least be able to tow the same weight the same speed on inclines? Nope - not even close. The Dodge with the poorer gearing does much better.

By the way, I also have a 69 Dodge truck with a 318 gas V8 and 4.88 axle gears. It couldn't do half the work of the other two trucks mentioned. I wonder why?

Gearing, wind resistance, friction, gearing versus torque-curve of the engine, peak horsepower at what RPM, etc. all play into it.

finally somebody else knows about northwest.run one everyday.man u talk about the torque out of those old machines.

Your trucks tops speed is limited by the hp at the rpm you are turning at top speed.

Your truck needs given amount of hp to push through the air based on the aerodynamics and rolling friction and that is pretty much it.

The gearing only matters such that you can be at peak hp when you are at your top speed. Too low of gears and your hp falls off and you don't get there. Too tall of gears, well, you'll be too far down the hp curve and you fall on your face when going for top gear.

I don't know what car you're talking about but 275 hp will certainly propel any weight of small aerodynamic car to 150 mph given it has tall enough gears to get there.

Have a look at jdemaris's post and other's of that theme. You can't make a teddy26forfood scheme work.

You are right so far, but it will be challenged.
I won't top this but I have gotten 58 MPH (straight run) with a 10 Hp stock Briggs in a Bolens Husky tractor'

We found the 10 Hp had better torque coming out of the turns an the 1/8 mile dirt track.
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It's not about "giving up". It just amazes me that when given a set of numerical parameters that are mathamatically valid and a set of mechaical principles that can not deviate why there is an understanding problem. It's simple, you come up with an answer to the equation using said parameters and princples only to have guys throw out theoritical stuff to invalidate the answer yet can't explain how or why the parameters could be as they were if the conclusion was not correct.

Just like a discussion several years ago about where to check backlash on a ring gear, closer to the inner diameter, the outer diameter, or in the middle. In reality it makes no difference as both the inner diameter, the outer diameter, and the middle all move the same amount in relation to the pinion gear. If they didn't then the tooth faces would not be parallel, which they are and in fact have to be or you'd end load the gears and break teeth. That discussion went on forever and when all was said and done there were still guys that just "didn't get it".

As for this discussion I'm done talking and debating whether 2+2 equals 4 or whether there is something I don't know about that changes that answer to 3 or maybe 5.... All I know is I was in the car and it scared the imortal sh!t out of me and whether it was 150 or 160 or 130, I'm never doing it again.....

What model do you run? I've done alot on the 80D's, the 95's and 9570's and a little bit on the old 41's. Als have experience with American, BE,Linkbelt, and Koehring. As for the NW machines you can't beat them, expecially with the Murphies. Those engines will pull the t!ts off of a bull. Got one guy in Chapel Hill that has an 80D with a front shovel we're waiting to get back on when the money gets right for him. He says it'll out dig a 345B CAT excavator all day long and never grunt hard. He also has a 190D dragline that is setting in pieces waiting to be assembled, again when the money is right. It doesn't have a Murphy but hey, a 12V-71 Detroit with a torque converter isn't such a bad deal for draglining either.
As far as efficiency and lugging cabability though you can't beat the Murphies. Got one customer put their 9570 NW to pasture for a yard larger, Linkbelt, hydraulic machine. Final tally by the operator was that the Linkbelt moved X yards per day and used about 130 gallons of fuel while the NW moved nearly twice the material and used about 40 gallons of fuel a day.....but the Linkbelt had A/C....

You gotta let it go.... It is not possble to convince people that haven't done anything,that things can be done. As for speed of a cubic inch rated older vehicle vs a new liter rated POS, it is two different worlds. Personally, I had a 66 Pontiac Catalina with 389 and a 2 barrel carb, automatic transmission that you could shift manually at 70 from low to second, and from second to high at 120. Top end was easily 140.. Yes, speedo was accurate. And that was a larger car body than a 55 Chevy. Wayne

Why have a 600 HP turbo diesel to pull a B train when all you need is 15 HP Briggs & Stratton. Now I know the real reason Cat got out of the truck engine business. It was BS, sorry B&S. Dave

70 Roadrunner 383 3.23 gears had to drive 40mph on speedo to go 55mph.Thats by state police radar.Had it to 148 on 150mph speedo.Took 5 miles to coast back to 55mph.Those telephone poles look like a picket fence,just like Johnny Cash said in his song.Thats the truth,don't know how fast it was,but it was as fast as i've been without wings.So can he go 150,sure.

I was trying to find a listing of top speed for muscle cars and didn't come up with much except this little excerpt from a Mopar website. It talks about the 1969 Daytona. What is interesting, aside from the 200mph top speed is that it achieved this through "extensive windtunnel testing" Hmmmm

Below are two excerpts from the web site.

"The Charger 500, with a Coronet grille and a flush rear window, was built by Creative Industries; 500 were sold in accordance with NASCAR rules. The main reason for the Charger 500 was to eliminate aerodynamic problems that hurt it in comparison to Ford's lower-power but more slippery racing models. Chrysler had an ace up their sleave, though: the product of extensive wind tunnel testing, the Charger Daytona included a massive rear spoiler and an aero nose. No other car could match it for top speed (200 mph), with its standard 440 and optional Hemi. Its looks, notable today, were not appreciated in 1969."

"One of the more interesting chapters in technological history was the 1969 Dodge Daytona. This vehicle had a drag coefficient (cd) of just 0.28, better than most cars made today. It would have produced even less drag, if it weren't for the tall spoiler (added to keep the rear wheels on the ground at high speeds). But, despite its 200 mph speed record (set by Buddy Baker on March 24, 1970, at 200.447 mph around Talladega), the car didn't sell well because people thought the aero look was ugly! The price, about $4,000, was high, but not insane."

Now I am not saying that this in any way validates what others are saying here because this was a very special car but my point is that aerodynamics played a huge role in this accomplishment.

Only way it could coast 5 miles would be down hill. Aerodynamic drag increases with the square of the speed.

Is it because the Cummins is an inline 6 that produces its power and torque at a more opportune rpm vs the Ford?

I have a question for you. Why is it that my CIH 7220 magnum with 180 hp 8.3 cummins will do way more work and lug better than my 350 hp Cummins powered Dodge. Even if you weighted them the same the tractor will do more work with less hp. Can you explain why.

Because you are comparing apples and oranges.
Put a pto on the truck transmission and connect to a dyno or electric generator. V.s. connect the tractor to the identical dyno or generator.
The truck will produce almost twice the power than the tractor.

Wayne and **40 are fascinated by typing 5000 words when about 20 would do. It"s a DISEASE, apparently with out a cure.

Let them live their fantasy!

Had a buddy who had a '67 AMC Rebel with a 290 V8 and a 3-speed overdrive transmission. The car would run 110 MPH in 2nd Overdrive, but only 90 in 3rd gear.

We always figured it was because of aerodynamics [or the lack thereof], combined with the torque curve of that specific engine. In 3rd, it just wasn't in the proper RPM range to make enough torque to propel that brick any faster. At least that was our theory.

Personally I would rather have a Lotus Omega. 3.6 litre Opel engine,twin turbo,6 speed ZF gearbox from a Corvette ZR-1 and a Holden Commodore Group A diff. Off the showroom floor, good for 177mph/285km.

To pull 80,000 lbs. at 70 MPH? Dave

Most diesels nowdays are governed for RPM so changing the gearing is going to have a direct relationship to speed.Most gas small trucks these days are geared way too high and if hauling anything or towing the top gears are mostly unusable.So the trick with gearing is to get the right ratio for what you'll be doing the majority of the time with your vehicle.

My Charger has 150 mph on speedometer Don't know how accurate it was but saw 147 on it one night, stripe on road looked solid..1970 charger 500 with 383 auto with 323 rear end, just plain 500 not Daytona...

I remember years ago when everybody was talking about a 4:11 gear for drag racing a Chevy car.So I put one in my car.It made it a gas guzzler and slowed it down.Maybe you got off the line a little quicker,but I could smoke them with the 3.92s and be going faster at the other end.In your example one engine is an inline engine,which by the way its made,has more torque,and the other is a V8 which might have more horsepower but less torque.If you have to choose between horsepower and torque,torque is going to be what you want.In my example I had a intake manifold called a Torker manifold and it really did give you low end torque.So there are mods that can give you torque and it means you can run a higher gear for speed if you dont have to sacrifice higher speed for lower gears.

In-line versus V-8 has little to do with any of this. An in-line engine with ladder-frame block construction is more rugged, but not more inherently powerful.

The Cummins 5.9 outdoes the Ford-IH V8 because it has much longer stroke, direct injection, and higher turbo-boost. The 94 Ford-IH 7.3 I mentioned has indirect injection, a max boost of 7 PSI, and a relatively short stroke (4.1") as compared to the Cummins (4.8").

Long stroke can give high torque in any engine, gas or diesel, regardless of V, Boxer, or in-line. Just not often done in V-8s.

Now . . . you say your CIH 7220 will "outwork" your Dodge truck? When is the last time you took your 7220 down the highway at 90 MPH?

Also, in general, wouldn't anybody assume that a bigger engine of similar design can do more overall work then a smaller one? So, you think your 505 cube engine can do more overall work than a 360 cube engine and you are surprised?

Anybody that screws around with engines knows that horsepower specs alone mean next to nothing.

You are wrong because nobody has said this yet,How much horsepower does it take to move the car or truck or anything you are trying to move?It never took 450 horsepower to move a tractor trailer.In the 1960s they had 180 horspower diesel engines,even smaller before that, in tractor trailers running 70 MPH.No turbo,and lots of gears,even 3 speed rear ends.A 13 speed transmission with 3 speed rear ends is 39 speeds.
A VW doesnt have a lot of horsepower,maybe 20 hp on the old air cooled ones,and they would go 70 or 80 mph.
In an ideal situation,you want enough horsepower to move you quickly,and a VW with 20 horsepower will move it alright.Say you rigged up a 5 horsepower motor with a lot of gears and you can still move the VW at 70 MPH on flat ground,it might take 3 or 4 time as long to get it there.
In the extreme example I gave about moving 80,000 pounds at 70 MPH on flat ground with a 15 horsepower motor,I even said that getting it started was what was hard.Plus Ill even say this,you just pull out the 450 horse power engine and put the 15 horsepoer rig in,but with another transmission hooked to the truck transmissin.The little motor will only put out so much power,but how do gears effect the power the engine puts out?There is underdrive as well as over drive.You would need torque multiplying gears,like my example of the wrench to get the truck transmission turning,but it can be done.So say the 15 horse engine puts out 10 ft pounds of torque,then you put it through an underdrive set of gears to put 100 ft pounds of torque on the transmission of the truck input shaft.Smarter people than me can figure out what gears it would take and how much would be lost to friction,but its possible.I dont care if it takes 3 hours or even all day to do it,Im saying it can be done.It would be too slow to be practical to use.

One time I ran out of fuel before I got to the top of the ramp with a fully loaded semi.In order to coast down into a gas station I pout the truck in gear,cranked the starter and the starter pulled the whole truck up the hill,around the corner and got it started coasting into the station.Not fast of course,but faster than you think.How many horse power does a starter motor have?I bet its not close to 15 horsepower.

Some of you all are handicapped by what you think you know.You have book learnin but no practical knowledge.Every discussion always has nay sayers,but some of you all,even sounding as if your argument has merit,dont know what you are talking about.Gears are how everything is done.Look at a tractor,its not fast,but it will pull a house down.Why?Gears.Gears work the other way too,which is why cars can go 150 MPH if you believe it or not?Just watch Nascar,they go over 180 now and did go 200.Did you know that in the beginning of Nascar up into the 1960s,they went and got a stock car without an engine and transmission and made a race car with it?If gears wont make a car fly,and solid lifter cams wont make an engine scream,you all better tell Nascar,but I dont think they will listen.This is really kid stuff.I grew up with kids that knew this stuff 40 years ago,and here you all are,being defeated by your own knowledge,or lack of knowledge.
So here is a question for you,when does my 15 horsepower motor not have enough horsepower to move the truck with enough gears?Can gears increase the torque put out by an engine?
There is always more than one way to skin a cat.Plus there are guys here who just post to run their mouth as if they know something,or to stir up trouble.You can figure out who.They never help any conversation,and drive off people who might have good replys.Just dont pay attention to them if you want to reply.

I know you are right.I have lived through it myself.Only one small thing is,and if you have a tach you can see it,when you are running flat out it pulls you down going up a hill and you loose some RPMS,going down the other side you will gain some RPMS.It would be hard to keep a constant speed unless you were on flat ground like the salt flats.So the ones talking about a speedometer have a point in that its not perfect,but your calculations are better than a speedometer if you have a tach.Back when I was a kid thats the first thing we did to a car was put a tach on it.My Impala SS had one from the factory in the dash.Thats how I figured how fast it would go,rpms,tire size,and rear end ratio.It might not run exactly that speed,but it would be close and might even be faster than the calculations because everybody reads a gauge different.Plus the tach could be low a little,or high.Anyway,I know you are right,they are not going to "get it"even if you prove it to them.
Its pretty cheesy for a guy to say a car wont run that fast because of aerodynamics,and you proved it could with mathematics,because if its turning that many RPMs,its going that fast.You might fly in a lighter car,but when I was a kid we jacked up the back of the car and I know that helped hold the back end down.My Chevelle with air shocks in the back,I jacked it up to where L60s wouldnt rub and you felt like you were sliding out of the seat.Aerodynamics is just another tool of running fast.You want more air to go over the top of the car,so raising the back would lower the front,and get more air on top of the car.The angle would increase the pressure on the back tires.You can still get airborne though.

very interesting listning to this debate.It does take Hp to do 150MPH but know one knows exactly how much. We all have driven a bicycle and each person only has X amount of Hp.When we drove single speed bikes some had big tires some had small,different gear ratios we could choose the fastest bike or the fastest take off bike.Then came the 5 speed 10 speed WHY? because it allowed you to get there faster with still the same person or HP.NOw we could speed up quickly and shift up till we were at the fastest speed we could get to.It took no more power to start than to finish(at least not that your body could feel)at the start you did 5MPH at the end you were doing 15-20maybe 25 MPH. You could never do that speed with a older low geared bike.YOu still had the same power but not the right gears to propell you to a faster speed.I think a bicycle is a way better way to show the diffrence that a single HP can do than say run a big rig with a 15 hp motor.I as a human can only produce so much power and when I started into the 18 speed bikes I know they uped my speed by a good notch and it wasn't because I gained power over night.

so all you who don't beleive a certain Hp can get a car of said weight to a certain speed you DO NOT KNOW HOW MUCH Hp THE DRAG, WIND RECISTANS FRICTION and all those other ghosts that hold back the car takes.until you sit in the drivers seat at that speed get of your a$$ and find a biycle and see how fast you can get in each gear and then come back here and let us all know what you found out about GEARS.

Between New Orleans and Slidell, Louisiana there is a bridge thats about 6 miles long over Lake Ponchatrain.It has a hill on each end,I assume for expansion.As I came over the hill going onto the bridge ,my truck sputtered and I ran out of fuel.I started it back up and got it up to about 70 and it died again and I coasted all the way to the other hill on the north end.I got it over that hill and had to siphon fuel out of the reefer to get off the end of the bridge.If the bridge was 6 miles long and say the hill is off the end of the bridge,plus it probably had a tail wind that day just being on the short side I would say 4 miles a tractor trailer coasted from 70 MPH.Its been a long time ago,but I think I had to start it up a couple of times to get to the other hill,but I know it never saw 70 MPH again,maybe 30,until it died.So yes its possible to coast a long ways on flat ground,even with a semi,which is way less aerodynamic than a car.

Hello NCWayne,
You stated that the R.P.M.'s, while you were doing 150 M.P.H., was 6000 to 6500.
Here is the formula to find R.P.M's.
I will use your figures.

The formula:

R.P.M's = MPH x GEAR RATIO x 336 / TIRE DIA.
150 x 3.23 x 336 = 162792 / 26.910828 = 6049 RPM's.

Pretty close to your claim.
Guido.

sure it wasnt commander cody's hot rod lincoln,guy beside me was white as a ghost!. bill m.

Yes but isnt HP work done over time?
I have never had my CIH doing 90mph but also I have never hooked my dodge to a nine shank chisel plow, which it wont pull.

Theoretically speaking 305 hp should do more work than 180 hp. right?

Yes but the tractor will produce twice the torque.

80-d shovel .got a 1955 41.and a 1985 model 6.bought the 80-d in 1977 when we done the bryson-city bypass for a-b burton.

There are many variables. One is that horsepower specs are not all based on the same thing. Some, especially with HD engines, are expressed with full-time hard use in mind and the engines are often derated. In fact, many are rated for the HP they make within their peak torque-curve only. Car and light truck engines are often expressed with peak power, not what they can sustain under constant use without falling apart.

Then of course there is SAE NET, SAE Gross, etc.

You asked if in theory, a 305 horse auto engine can do more work than a 180 horse tractor engine. The answer is yes, but only for certain jobs and only if longevity doesn't count. The 180 horse engine is apt to do more overall work in its life. To be technical, if both are rated with the same forumla, the 305 horse engine will do more work then the 180 horse engine until it craps out. In regard to your nine shank chisel plow? If the 350 horse Dodge-Cummins was hooked to it, it certainly would pull it at a certain speed if all was geared properly. I don't have specs here, but I assume it has to run at much higher RPMs to make that 350 horse than the 180 horse engine in the tractor. I'm also going to assume that if you did such a thing, the 350 horse engine would not last near as long at the 180 horse tractor engine. For hard pulling, I'd pay much more attention to cubic inches and peak torque then any HP specs.

Twice the torque?Where are you numbers from a dyno or even extrapolated from factory specs?
If both engines make peak HP at 2100rpm. The 350HP engine will be making double the torque of the 180HP engine.
Do you know the formula for HP?

How did so many people get out of school before learning basic math and physics?

Yep, stripe looked solid and the trees you could see looked like a picket fence.

Wayne, you misunderstand what horsepower is. It is the rate at which you can do work, "work" defined as applying a force through a distance. That force may be causing acceleration (F=ma), it may be overcoming friction (aerodynamic or rolling resistance), or it can be lifting weight against gravity. In the case of a car accelerating uphill, the engine is doing all three.

I have read your fantastic posts about your 150 mph Chevy; if you say it's true, then I guess it must be so. But it is HORSEPOWER, not gearing, that got you up to 150. If all you needed to go fast is the right gears, then every rice-burner with a five-speed overdrive transmission would go over 140 mph. Fact is, most cars cannot maintain the same top speed in overdrive that they can in the next higher gear: the power isn't there to overcome aerodynamic resistance.

We had a '55 Studebaker that would run 115 MPH in second gear overdrive, but would slow to around 105 when shifted into high (3rd) gear overdrive.

It was a neat little car, and it surprised a lot of stopsign racers on the takeoff.

Paul

I do have math skills. I was just going on what the brochure said about the tractor. Iam glad though that I am not an engineer of any sort.

Hello traditional farmer,
All diesel engines need a governor. The throttle controls the fuel not the air, so a governor will limit its rpm's. that is why some of them will run away if they intake fuel in the air system. I have seen some do that, not a pretty sight. parts will come off the engine faster that you can run.
Guido.

Best example I recall was Honda 350 1972. Had six gears and fifth would outrun fourth. Maybe I was too heavy. Sixth couldn't pull me as fast as fifth. Long time ago. Dave